WO2022198584A1

WO2022198584A1 - Charging method, charging apparatus, and charging device

Info

Publication number: WO2022198584A1
Application number: PCT/CN2021/083056
Authority: WO
Inventors: 魏红梅; 陈茂华; 胡乔舒
Original assignee: 宁德新能源科技有限公司
Priority date: 2021-03-25
Filing date: 2021-03-25
Publication date: 2022-09-29
Also published as: CN114531928A; CN114531928B

Abstract

The present application discloses a charging method for a rechargeable apparatus, a charging apparatus, and a charging device. The charging method comprises a constant-current charging phase and a constant-voltage charging phase. In the constant-current charging phase, standing and/or negative charging is performed at least once when constant-current charging reaches 10% to 90% SOC, the time period for each instance of standing being T₁, T₁≥30s, and the time period for each instance of negative charging being T₂, T₂≥10s. The charging method of the present application can improve the cyclic performance of a lithium metal battery.

Description

Charging method, charging device and charging device

technical field

The present application relates to the field of energy storage, and in particular, to a charging method, a charging device and a charging device.

Background technique

Lithium metal is the metal with the smallest relative atomic mass (6.94) and the lowest standard electrode potential (-3.045V) among all metal elements, and its theoretical gram capacity can reach 3860mAh/g. Therefore, using lithium metal as the negative electrode of the battery, with some high energy density positive electrode materials, can greatly improve the energy density of the battery and the working voltage of the battery. However, if lithium metal as a negative electrode material is truly commercialized, there are some problems that must be solved: 1) Li metal itself is highly reactive, especially the freshly formed lithium metal, which is very easy to electrolyze with existing small organic molecules. A series of side reactions occur in the liquid system, resulting in the consumption of lithium metal and the electrolyte at the same time, and the cyclic coulombic efficiency is generally less than 99.5%. (greater than 99.9%); 2) During the charging process of lithium metal batteries, lithium will be deposited on the surface of the negative electrode current collector. Due to the non-uniformity of the current density and the concentration of lithium ions in the electrolyte, the deposition rate of some sites is too fast during the deposition process, resulting in the formation of sharp dendrites. The presence of lithium dendrites can lead to a great decrease in deposition density, resulting in lower energy density. In severe cases, the diaphragm may be pierced to form a short circuit, causing safety problems. 3) With the charging-discharging of the lithium metal negative electrode, the thickness of the negative electrode plate will undergo a violent expansion-shrinkage. The thickness of the expansion and contraction is related to the amount of active material per unit area of the cathode and the gram capacity of the active material, and is also related to the deposition of lithium. The density and the volume of the side reaction products are related. According to the general design of the current commercial lithium-ion battery, the thickness change of the single-sided lithium metal anode from full charge to full discharge will reach 8 μm to 100 μm. This will cause the interface between the negative pole piece and the less flexible inorganic protective coating to peel off and lose the protective effect. 4) The charging rate is low. In the case of a large charging rate, the deposition of lithium metal is more likely to be uneven, aggravate the growth of lithium dendrites, and the size of lithium metal particles will also become smaller, increasing the side reaction area with the electrolyte, resulting in electrolyte and lithium metal. Consumption accelerates, cycle decay accelerates, and even diving occurs.

SUMMARY OF THE INVENTION

The purpose of this application is to improve the cycle performance of lithium metal batteries by over-optimizing the charging process. In order to achieve the above object, the present application provides a charging method, a charging device and a charging apparatus for a rechargeable device.

In a first aspect, the present application provides a charging method for a rechargeable device, the charging method including a constant current charging stage and a constant voltage charging stage, wherein in the constant current charging stage, the constant current charging is carried out to 10% to 90% Perform at least one rest and/or at least one negative charge at the SOC, wherein the time for each rest is T ₁ , T ₁ ≥ 30s, and the time for each negative charge is T ₂ , T ₂ ≥ 10s.

According to some embodiments of the present application, the charging method includes the following steps:

(1) The rechargeable device is charged with a first constant current until 10% to 90% SOC;

(2) statically and/or negatively charging the rechargeable device after the first constant current charging;

(3) carrying out the second constant current charging on the rechargeable device after standing and/or negative charging;

(4) performing constant voltage charging on the chargeable device after the second constant current charging.

According to some embodiments of the present application, the anode of the rechargeable device contains lithium metal or an alloy of lithium metal.

According to some embodiments of the present application, _{1min≤T1≤4min} , and _{30s≤T2≤4min} .

According to some embodiments of the present application, the number of times of standing is 1 to 10 times, and the number of times of negative charging is 1 to 5 times.

According to some embodiments of the present application, in the constant current charging stage, the charging capacity of the current I ₊ of the constant current charging is Q ₊ , and the charging capacity of the current I _- of the negative charging is Q ₋ , where Q ₊ >Q ₋ .

According to some embodiments of the present application, each negative charge capacity Q- satisfies _: 1%Q<Q-<10%Q, preferably 2%Q≤Q-≤5%Q, where Q is the sum of Q ₊ and Q- Difference.

According to some embodiments of the present application, the negative charging current I ₋ and the constant current charging current I ₊ satisfy: 3≦I ₋ /I ₊ ≦20, preferably 3≦I ₋ /I ₊ ≦6.

According to some embodiments of the present application, the current I ₊ of the constant current charging satisfies: 0.1C≤I ₊ ≤0.5C.

According to some embodiments of the present application, the negative charging has any one of the following characteristics A) to C): A) the current I- of the negative charging remains unchanged; B) the current I- of the negative charging is The first change slope increases, and then decreases with the second change slope; C) the negative charging current I- increases with the first change slope, maintains for a period of time, and then decreases with the second change slope.

According to some embodiments of the present application, the first change slope k1 satisfies: 0.0167C/s≤k1≤0.2C/s. According to some embodiments of the present application, the second change slope k2 satisfies: 0.0167C/s≤k2≤0.2C/s.

According to some embodiments of the present application, a first variable current charging is further included between steps (1) and (2). According to some embodiments of the present application, in the first variable current charging, the first forward current I ₁ decreases with a third change slope. According to some embodiments of the present application, the third change slope k3 satisfies: 0.0167C/s≤k3≤0.2C/s.

According to some embodiments of the present application, a second variable current charging is further included between steps (2) and (3). According to some embodiments of the present application, in the second variable current charging, the second forward current I ₂ increases at a fourth change slope. According to some embodiments of the present application, the fourth change slope k4 satisfies: 0.0167C/s≤k4≤0.2C/s.

In a second aspect, the present application provides a charging device, the charging device comprising: a constant current charging module; a stationary module and/or a negative charging module for performing constant current charging to 10% to 90% SOC At least one standstill and/or at least one negative charge, wherein the time for each stand is T ₁ , T ₁ ≥ 30s, and the time for each negative charge is T ₂ , T ₂ ≥ 10s; constant voltage charging module , used for constant voltage charging of rechargeable devices after constant current charging.

In a third aspect, the present application provides a charging device comprising a memory and a processor, where the memory is used for storing executable program codes, and the processor is used for reading the executable program codes stored in the memory to execute the charging method described in the first aspect of the present application.

Description of drawings

FIG. 1 is a current trend change diagram of a conventional charging method in the prior art.

FIG. 2 is a schematic diagram of current trend changes of charging methods according to some embodiments of the present application.

FIG. 3 is a schematic diagram of current trend changes of charging methods according to some embodiments of the present application.

FIG. 4 is a schematic diagram of current trend changes of charging methods according to some embodiments of the present application.

FIG. 5 is a schematic diagram of current trend changes of charging methods according to some embodiments of the present application.

FIG. 6 is a schematic diagram of current trend changes of charging methods according to some embodiments of the present application.

FIG. 7 is a schematic diagram of current trend changes of charging methods according to some embodiments of the present application.

FIG. 8 is a schematic diagram of current trend changes of charging methods according to some embodiments of the present application.

Detailed ways

In order to make the invention purpose, technical solution and technical effect of the present application clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments given in the specification of the present application are only for explaining the present application rather than limiting the present application, and the present application is not limited to the embodiments given in the specification.

In a first aspect, the present application provides a charging method for a rechargeable device, the charging method including a constant current charging stage and a constant voltage charging stage, wherein in the constant current charging stage, the constant current charging is carried out to 10% to 90% The SOC performs at least one rest and/or at least one negative charge, wherein the time for each rest is T ₁ , T ₁ ≥ 30s, and the time for each negative charge is T ₂ , and T ₂ ≥ 10s.

The static process is to eliminate the electrochemical and concentration polarization process of the cell. The negative charging process has two effects: one is to eliminate lithium dendrites with an instantaneous negative current; the other is to eliminate the polarization process.

In this application, the term "SOC" is defined as charge capacity/theoretical capacity.

In this application, C represents the current rate, and C=current/capacity.

According to some embodiments of the present application, in the constant current charging stage, at least one rest is performed when the constant current charging reaches 10% to 90% SOC. According to some embodiments of the present application, the standing time T ₁ satisfies 1 min≤T ₁ ≤4min. In some embodiments, T ₁ is 1 min, 1.5 min, 2 min, 2.5 min, 3 min, or 3.5 min.

According to other embodiments of the present application, in the constant current charging stage, at least one negative charge is performed when the constant current charging reaches 10% to 90% SOC. According to some embodiments of the present application, the negative charging time T ₂ satisfies 10s≦T ₂ ≦4min. In some embodiments, _{30s≤T2≤4min} . In some embodiments, ₁ min≤T2≤4min. In some embodiments, T ₂ is 1 min, 1.5 min, 2 min, 2.5 min, 3 min, or 3.5 min.

In this application, the rechargeable device may be a lithium metal battery. According to some embodiments of the present application, the anode of the rechargeable device contains lithium metal or an alloy of lithium metal. Specifically, the lithium metal alloy is Li _x M, wherein M is selected from one or more of Al, Mg, In, Sn, and B.

According to an embodiment of the present application, in the constant current charging phase, constant current charging to 10% to 90% SOC, eg 10% SOC, 15% SOC, 20% SOC, 25% SOC, 40% SOC, 50% SOC, 60 %SOC, 70% SOC or 80% SOC for first negative charge or rest. In some embodiments, constant current charging to 10% to 40% SOC for negative charging or resting.

According to some embodiments of the present application, the frequency of negative charging may be one time in a single circle, or one time in multiple circles, and the multiple circles may be every 5 circles or every 10 circles or every 20 circles or every 50 circles, preferably a single circle Circle once.

According to some embodiments of the present application, the charging method includes the following steps: (1) performing a first constant current charging on the rechargeable device until 10% to 90% SOC; (2) charging the rechargeable device after the first constant current charging The charging device performs static and/or negative charging; (3) the rechargeable device after static and/or negative charging is subjected to second constant current charging; (4) after the second constant current charging The rechargeable device is charged with constant voltage.

According to some embodiments of the present application, the number of times of standing is n, and 1≤n≤10. According to some embodiments of the present application, the number of times of negative charging is m, where 1≤m≤5. According to some embodiments of the present application, standing can be used multiple times, and the interval time can be of equal length, or consistent with the anodic polarization overpotential, or other variation laws. According to some embodiments of the present application, the negative current may be used multiple times, and the interval time may be equal, or consistent with the anodic polarization overpotential, or may be other variation laws.

According to some embodiments of the present application, in the constant current charging stage, the charging capacity of the constant current charging is Q ₊ , the charging capacity of the negative charging is Q ₋ , and the charging capacity of the constant current charging is greater than the charging capacity of the negative charging, that is, Q ₊ > Q _- . According to some embodiments of the present application, each negative charge capacity Q ₋ satisfies: 1%Q<Q−<10%Q, where Q is the difference between Q ₊ and Q− (the charge capacity of constant current charging and the negative charge difference in charging capacity). In some embodiments, 2%Q≤Q-≤5%Q. In some embodiments, 3%Q≤Q-≤4%Q.

According to some embodiments of the present application, the negative charging current I ₋ and the constant current charging current I ₊ satisfy: 3≦I ₋ /I ₊ ≦20, preferably 3≦I ₋ /I ₊ ≦6. According to some embodiments of the present application, the current I ₊ of the constant current charging satisfies: 0.1C≤I ₊ ≤0.5C. As mentioned above, the negative current needs to eliminate lithium dendrites. Under the condition of high current, it has a stronger tip effect, eliminates lithium dendrites more thoroughly, improves the anode interface, and prolongs the cycle life.

There are three ways from the forward current to the static or short-term negative current. The first method is to change the forward current stepwise to the negative current. For example, the charging current suddenly changes from 1C to the negative maximum negative current -Cmax. The direction pulse is a negative current (as shown in Figure 2), and its ladder means that the positive current changes directly to the negative current, during which the current does not gradually change continuously. 1C suddenly changes to 0C, at this time, the negative pulse is that the negative current gradually increases continuously from 0 to the maximum negative current -Cmax (as shown in Figure 4); the third method is that the positive current gradually decreases to 0, and the negative current It gradually decreases from 0 to the maximum negative current Cmax with the same change slope (as shown in Figure 5).

According to some embodiments of the present application, the negative charging process uses a continuously changing current, the current changing slope is 0.0167C/s≤k≤0.2C/s, preferably the current changing slope k=0.033C/s. According to some embodiments of the present application, the negative charging process uses the negative current I ₋ to satisfy: 0.2C≦I ₋ ≦2C, such as 0.5C, 0.8C, 1.0C, 1.5C, and the like.

According to some embodiments of the present application, during the negative charging process, the forward current continuously changes to the negative current, and the current change slope is 0.02C/s≤k≤0.22C/s, for example, k=0.0367C/s.

According to some embodiments of the present application, the first change slope k1 satisfies: 0.0167C/s≤k1≤0.2C/s. According to some embodiments of the present application, the second change slope k2 satisfies: 0.0167C/s≤k2≤0.2C/s. According to some embodiments of the present application, a first variable current charging is further included between steps (1) and (2). According to some embodiments of the present application, a second variable current charging is further included between steps (2) and (3). According to some embodiments of the present application, in the first variable current charging, the first forward current I ₁ decreases with a third slope of change, and in the second variable current charging, the second forward current I ₂ decreases with the third 4. The slope of change increases. According to some embodiments of the present application, the third change slope k3 satisfies: 0.0167C/s≤k3≤0.2C/s. According to some embodiments of the present application, the fourth change slope k4 satisfies: 0.0167C/s≤k4≤0.2C/s.

According to some embodiments of the present application, the charging device is configured to execute the charging method described in the first aspect of the present application.

The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program codes.

1. Preparation of Lithium Metal Batteries

Positive electrode: The positive electrode is composed of a mixture of 96.7% LiCoO ₂ +1.7% PVDF (binder) + 1.6% SP (conducting agent), which is coated on the surface of the positive current collector aluminum foil. After cold pressing, the length and width are 42.5mm. The 49.5mm square piece is ready for use;

Negative electrode: Punch the ready-made lithium-coated copper foil into square pieces with a length and width of 44mm and 51mm, respectively;

Electrolyte: In a dry argon atmosphere, organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of EC:EMC:DEC=30:50:20 , and then add lithium salt lithium hexafluorophosphate (LiPF ₆ ) to the organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15M;

Isolation film: use polyethylene (PE) with a thickness of 15um and cut it into rolls with a width of 47.2mm for use;

Assemble the fabricated cathode, anode and diaphragm into a laminated battery, inject liquid, complete standing, formation, capacity test, and conduct cycle test.

2. Charging method

The following examples and comparative examples all use the above-mentioned lithium metal batteries for charging.

Comparative Example 1:

At 25 °C, the conventional CC-CV charging method is used to charge the lithium metal battery, as shown in Figure 1, which includes the following steps:

(1) Constant current charging stage: charge with 0.2C constant current until the cut-off voltage is 4.45V;

(2) Constant voltage charging stage: charge at a constant voltage of 4.45V to a cut-off current of 0.05C.

In this comparative example, during the charging process of lithium metal, lithium is deposited on the surface of the anode, and the polarization of the battery itself causes a concentration gradient on the surface of the anode, resulting in uneven current distribution on the surface of lithium metal, which further deteriorates the deposition morphology of lithium metal. Sharp-like substances, the specific surface area increases, the side reactions increase, and the cycle decay is accelerated.

Example 1

At 25°C, charging a lithium metal battery, as shown in Figure 2, includes the following steps:

(1) The first constant current charging stage: charge at 0.2C constant current to 20% SOC;

(2) Negative charging stage: then charge with a single step negative current of 1C for 2min (3.3%Q);

(3) The second constant current charging stage: continue to charge with 0.2C constant current until the cut-off voltage is 4.45V;

(4) Constant voltage charging stage: After reaching the cut-off voltage of 4.45V, constant-voltage charging is performed until the cut-off current is 0.05C.

During the cycle test, each cycle of charging is carried out according to the above steps, as shown in Figure 7. The results are shown in Table 1.

Examples 2 to 4

The only difference from Example 1 is that the state of charge at the start of negative charging is different, where Example 2 is 40% SOC, Example 3 is 60% SOC, and Example 4 is 80% SOC.

Examples 5 to 7

Embodiments 5 to 7 differ from Embodiment 1 only in that the parameters of the negative charging phase in step (2) are adjusted, wherein:

Example 5 is to use a single step negative current 2C to charge, and the time is 1min (3.3%Q);

Example 6 is to use a single step negative current 1C to charge, and the time is 3min (4.95%Q);

Example 7 uses a single step negative current 2C to charge for 3min (9.9%Q).

Example 8

At 25°C, charging a lithium metal battery, as shown in Figure 3, includes the following steps:

(2) The first negative charging stage: then use a single step negative current 1C to charge for 2min (3.3%Q);

(3) The second constant current charging stage: continue to charge at 0.2C constant current to 80% SOC;

(4) The second negative charging stage: then use a single step negative current 1C to charge, and the charging time is 2min (3.3% SOC);

(5) The third constant-direction charging stage: continue to charge at a constant current of 0.2C to a cut-off voltage of 4.45V;

(6) Constant voltage charging stage: After reaching the cut-off voltage, constant-voltage charging to cut-off current of 0.05C.

During the cycle test, each cycle of charging is carried out according to the above steps.

Example 9

At 25°C, charging a lithium metal battery includes the following steps:

(1) The first constant current charging stage: charge at 0.2C constant current to 40% SOC;

(2) The first negative charging stage: then use a single step negative current 1C to charge for 2 minutes (3.3% SOC);

(3) The second constant current charging stage: continue to charge at 0.2C constant current to 60% SOC;

Example 10

The charging method is basically the same as in Example 1, except that in the cycle test, the first cycle is exactly the same as in Example 1, and the second to fifth cycles are charged according to conventional CC-CV (ie, there is no negative charging stage), and The 6th lap continues to follow the charging method of the 1st lap, that is, repeats every 5 laps, as shown in Figure 8.

Example 11

The charging method is basically the same as in Example 1, except that in the cycle test, the first cycle is exactly the same as in Example 1, and the 2-9 cycles are charged according to conventional CC-CV (ie, there is no negative charging stage), and The 11th lap continues to follow the charging method of the 1st lap, which is repeated every 10 laps.

Example 12

The charging method is basically the same as that of Example 8, the difference is that during the cycle test, the first cycle is carried out according to Example 8, and the second to fifth cycles are charged according to the conventional CC-CV charging method of Comparative Example 1, that is, every 5 cycles is repeated. .

Example 13

At 25°C, charging the lithium metal battery, as shown in Figure 4, includes the following steps:

(2) Negative charging stage: use a single negative current charging, in which the negative current gradually changes from 0 to the maximum negative current 1C at a rate of change of 0.033C/s, and is charged with a negative current of 1C for a certain period of time, and then The negative current gradually changes from 1C to 0 at a rate of change of 0.033C/s, and the negative charging stage lasts for 2min (3.3%Q);

(4) Constant voltage charging stage: After reaching the cut-off voltage, the 4.45V constant voltage is charged to the cut-off current of 0.05C.

Example 14

At 25 °C, the lithium metal battery is charged, as shown in Figure 5, which includes the following steps:

(2) The first variable current charging stage: the current gradually decreases from 0.2C to 0 at a rate of change of 0.0367C/s;

(3) Negative charging stage: charge with a single negative current, in which the negative current gradually changes from 0 to the maximum negative current of 1C at a rate of change of 0.0367C/s, and then the negative current is charged at a rate of 0.0367C/s. The rate of change gradually changed from 1C to 0, and the negative charging stage lasted for 2min (3.3%Q);

(4) The second variable current charging stage: the current gradually increases from 0 to 0.2C at a rate of change of 0.0367C/s;

(5) The second constant current charging stage: continue to charge with 0.2C constant current until the cut-off voltage is 4.45V;

(6) Constant voltage charging stage: After reaching the cut-off voltage, the 4.45V constant voltage is charged to the cut-off current of 0.05C.

Example 15

At 25°C, charging a lithium metal battery includes the following steps:

(2) Resting stage (current is 0): resting time is 1min;

(4) Constant voltage charging stage: after reaching the cut-off voltage, constant-voltage charging to cut-off current 0.05C.

Repeat the above steps for each lap for the loop test.

Example 16

At 25°C, charging the lithium metal battery, as shown in Figure 6, includes the following steps:

(2) The first resting stage: the resting time is 1min;

(4) The second resting stage: the resting time is 1min;

Repeat the above steps for each lap for the loop test.

Table 1

From the comparison between the comparative example and the comparative example, it can be seen that increasing the static or negative charging for a specific time (eg, 1 min to 3 min) in the constant current charging stage is beneficial to improve the cycle performance of the lithium metal battery.

Comparing Examples 1 to 4, it can be seen that when the initial SOC of negative charging is lower than 50% SOC, preferably 10% to 40% SOC, it is helpful to further improve the cycle performance of lithium metal batteries. Comparing Example 1 and Example 5, it can be seen that when 3≤I ₋ /I ₊ ≤9, the cycle performance of the lithium metal battery can be further improved. Comparing Examples 1, 6 and 7, it can be seen that when 2%Q≤Q-≤5%Q, the cycle performance of the lithium metal battery can be further improved.

Those of ordinary skill in the art can understand that all or part of the steps of implementing the above method embodiments may be completed by program instructions related to hardware. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps including the above method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the present application.

Claims

A charging method for a rechargeable device, comprising a constant current charging stage and a constant voltage charging stage, wherein in the constant current charging stage, at least one standstill and/or at least one negative charge is performed when the constant current is charged to 10% to 90% SOC The charging in the negative direction is T 1 , and T 1 ≥ 30 s, and the time of each negative charging is T 2 , and T 2 ≥ 10 s.
The charging method according to claim 1, comprising the steps of:

(1) The rechargeable device is charged with a first constant current until 10% to 90% SOC;

(2) statically and/or negatively charging the rechargeable device after the first constant current charging;

(3) carrying out the second constant current charging on the rechargeable device after standing and/or negative charging;

(4) performing constant voltage charging on the chargeable device after the second constant current charging.
The charging method of claim 1, wherein the anode of the rechargeable device contains lithium metal or an alloy of lithium metal.
The charging method according to claim 1 , wherein 1min≤T1≤4min, and 30s≤T2≤4min .
The charging method according to claim 1, wherein the number of times of standing is 1 to 10 times, and the number of times of negative charging is 1 to 5 times.
The charging method according to claim 1, wherein, in the constant current charging stage, the charging capacity of the current I + of the constant current charging is Q + , the charging capacity of the current I - of the negative charging is Q − , and Q + >Q - .
The charging method according to claim 6, wherein, each negative charge capacity Q- satisfies : 1%Q<Q-<10%Q, preferably 2%Q≤Q-≤5%Q, wherein Q is Q + difference from Q-.
The charging method according to claim 1 , wherein the negative charging current I − and the constant current charging current I + satisfy: 3≦I − /I + ≦20, preferably 3≦I − /I + ≦6.
The charging method according to claim 1, wherein the current I + of the constant current charging satisfies: 0.1C≤I + ≤0.5C.
The charging method according to claim 1, wherein the negative charging has any one of the following characteristics A) to C):

A) The negative charging current I - remains unchanged;

B) the negative charging current I - increases with a first change slope and then decreases with a second change slope;

C) The negative charging current I − increases with a first change slope, maintains for a period of time, and then decreases with a second change slope.
The charging method according to claim 10, wherein the first change slope k1 satisfies: 0.0167C/s≤k1≤0.2C/s; the second change slope k2 satisfies: 0.0167C/s≤k2≤0.2C/s.
The charging method according to claim 2, wherein between steps (1) and (2), it further comprises a first variable current charging; and/or between steps (2) and (3), it further comprises a second variable current charging. current charging.
The charging method according to claim 12, wherein, in the first variable current charging, the first forward current I 1 decreases with a third change slope; and/or in the second variable current charging, the second The forward current I 2 increases with a fourth change slope.
The charging method according to claim 13, wherein the third change slope k3 satisfies: 0.0167C/s≤k3≤0.2C/s; and/or the fourth change slope k4 satisfies: 0.0167C/s≤k4≤0.2C /s.
A charging device, comprising:

Constant current charging module;

A resting module and/or a negative charging module for performing at least one resting and/or at least one negative charging when the constant current is charged to 10% to 90% SOC, wherein the time of each resting is T 1 , T 1 ≥ 30s, the time of each negative charge is T 2 , T 2 ≥ 10s;

The constant voltage charging module is used for constant voltage charging of the rechargeable device after constant current charging.
A charging device includes a memory and a processor, the memory is used for storing executable program code;

The processor is configured to read the executable program code stored in the memory,

to perform the charging method of any one of claims 1 to 14 .